Communicating my thoughts on software development

Posts Tagged ruby

Some days ago I was developing a task on a Gradle project and I faced with a situation where I had to convert a Map < String, List < String >> to List < Pair >, each pair containing the key and one element from the List.

I decided to compare the solution in three different languages: Java 8 (using lambdas and the Streams API), Groovy and Ruby to see how concise and expressive they would be. Then, I created the Groovy code and it looked like this:

The Groovy and Ruby version are very expressive and concise. Note the use of the collectMany method on the Groovy version and the use of the flatten method on the Ruby version to flatten the result list into a single list of pairs.
The Java 8 version made use of the collect method of the Stream API, to collect the results in a list of Pair instances, each one holding the key and value of each element from the List< String >.

You probably already know what a palindrome is: a string to results in the same word, whether read left to right, or right to left. A K Palindrome is when a string can be tranformed into a palindrome by changing K characters at most. Regular palindromes have K=0.

Your challenge today is to write a method which takes a string and a value for k and returns true if it the string qualifies as a K palindrome.

Below is the code in Ruby. Our input string is omississimo and it’s a 0 palindrome String.

I like to solve this kind of tasks with programming languages (mainly the dynamically-typed ones..) I don’t know very much because it’s an opportunity to put my hands on them! This way I could experience Ruby’s closures syntax, it was really nice and I’m gonna try something new with it often!

There is a nice interview with the Twitter development team on Artima about using Scala in production on Twitter code. The team talks about some issues and facilities regarding the chose of Scala to develop Twitter’s queueing system and how Scala affected the team’s programming style.

My personal highlights:

And Ruby, like many scripting languages, has trouble being an environment for long lived processes. But the JVM is very good at that, because it’s been optimized for that over the last ten years..

So Scala provides a basis for writing long-lived servers…Another thing we really like about Scala is static typing that’s not painful. Sometimes it would be really nice in Ruby to say things like, here’s an optional type annotation

And because Ruby’s garbage collector is not quite as good as Java’s, each process uses up a lot of memory. We can’t really run very many Ruby daemon processes on a single machine without consuming large amounts of memory

In some cases we just decided to burrow down and use the Java collections from Scala, which is a nice advantage of Scala, that we have that option..

As I’ve learned more Scala I’ve started thinking more functionally than I did before. When I first started I would use the for expression, which is very much like Python’s. Now more often I find myself invoking map or foreach directly on iterators..

The reason you should care about immutability is that if you’re using threads and your objects are immutable, you don’t have to worry about things changing underneath you..